CONDENSERS. 



FIG. 151. 



bound electricity. This change is shown by less divergence of &. 

 Consequently J3 can receive more electricity from the machine 

 which will attract more 

 negative electricity to 

 n. This further sup- 

 ply will in turn bind 

 more of the positive 

 electricity of B at m. In 

 this way a large quan- 

 tity of positive elec- 

 tricity may be accumu- 

 lated at m, and a large 

 quantity of negative at 

 n. This accumulation 

 may thus go on until 

 the intensity at the 

 surface, p, is equal to 

 that of the machine, as 

 it was when A was absent. Interrupting communication by x and y, 

 both plates are charged. The vertical pendulum a shows no free 

 electricity, the electricity of A being all bound at n ; the pendulum 

 at 6 shows some free electricity, although the greater part of the 

 electricity of B is bound at m. Remove A and B from each other, 

 and the bound electricity of each is set free, and both a and b are 

 widely divergent. The complete apparatus is represented by Fig. 151. 



353. The Leydeii Jar. The Leyden jar consists of 

 a glass jar coated within and without for about two-thirds 

 its height with tinfoil. The mouth of the jar is closed 

 with a cork through which passes a metallic rod, commu- 

 nicating by means of a small chain with the inner 

 coat and terminating above in a knob. The cork 

 and the upper part of the jar are generally coated 

 with sealing-wax or shellac varnish to lessen the 

 deposition of moisture from the air. It is evi- 

 dently a modified electric condenser. The inner 

 coat represents the collecting plate B ; the glass 

 jar, the insulator plate (7; the outer coat the 

 FIG. 152. condensing plate A (Fig. 150). 



